This invention relates to electric drive units, in general, and to windshield wiper motor and gear units, in particular. In one known windshield wiper motor a worm shaft driven by an electric motor mates with two worm wheels located on opposite sides of the worm shaft, so that bending of the shaft is avoided. The torque generated by the drive motor is divided, so that there are favourable conditions with respect to rolling pressure and tooth pressure of the worm wheels. The two worm wheels rotate in opposite directions, so that the axial thrusts they exert are added up. The axial thrusts are created because of the inertia of the toothed wheels, forces exerted on other moving parts of a windshield wiper installation and because of the friction forces between the parts moved relative to one another. Thereby the efficiency of the entire electric drive unit is diminished.
It is one object of the invention to provide an electric drive unit, especially a wiper motor having a high efficiency wherein the friction forces appearing between the gearing members are as small as possible.